What we know about AIDS explains the essential science of HIV succinctly and clearly. It was originally published as a chapter in Debunking Delusionsby Nathan Geffen. With the permission of the author, Nathan Geffen, and the book's publisher, Jacana, we are now releasing this chapter under the Creative Commons Share-Alike 3.0 Unported license. Please feel free to copy and distribute it. You are also allowed to modify it under the terms of the license. Debunking Delusions can be purchased online from amazon.com and kalahari.net.